The takedown of the Hansa dark web marketplace, done live on national TV by Dutch police, was possible because officers had been running the site themselves – and on Thursday they detailed how they did it.

In 2016, security shop Bitdefender tipped off the Dutch plod that Hansa, one of the most popular dark web markets, was being hosted in the Netherlands. Hansa’s popularity was largely down to its multi-signature Bitcoin handling, which stopped buyers getting ripped off by not releasing payment until an order arrived.